One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's a good idea to figure out when to plant bunching onions by referring to the USDA zone info for Cupertino.

Planting Calendar for Bunching Onions

Frost tolerance for bunching onions:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Bunching Onions do ok in some cold which tells us that you can plant them a bit earlier in the year than other frost tender plants.

The earliest that you can plant bunching onions in Cupertino is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant bunching onions and expect a good harvest is probably September. If you wait any later than that and your bunching onions may not have a chance to really do well. If you are starting your bunching onions indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Cupertino the average date of last frost happens on February 15. You should expect an average low temperature of 25°F in the coldest months of winter.

Remember that USDA zone info for Cupertino may not be accurate from year to year and the actual date of last frost will vary from year to year. Half of the time in Cupertino you get surprised by a frost after February 15 so always be ready to cover your bunching onions in the event of a late frost.

USDA Zone Info for Cupertino

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Cupertino

You may be interested in your other planting guides for Cupertino.